Aerodrome and Ground Movement Control
The aerodrome team
Clearance delivery issues route and SSR clearances, ground control handles taxi and apron movement, tower controls runway operations and the circuit. Every aerodrome controller must know the declared distances: TORA (take-off run available), TODA (TORA plus clearway), ASDA (TORA plus stopway) and LDA (landing distance available, excluding clearway and stopway).
Runway in use is chosen primarily from surface wind, then constrained by traffic, taxiway layout, noise and runway condition. Surface movement radar, A-SMGCS and stop bars support operations in low visibility.
Runway safety
Runway incursion prevention is the core skill: positive crossing clearances, readback of holding instructions, keeping ILS critical areas clear in low visibility, and avoiding conditional clearances that depend on an aircraft vacating the runway. Low visibility procedures bring CAT II/III holding points and protected areas into force.
Phraseology traps
'Line up and wait' is not a take-off clearance. 'Cleared to land' with preceding traffic requires assurance the runway will be vacated. Conditional clearances need the condition to be visible to both pilot and controller and must never be used to cross a runway. Never say 'take off' before issuing the clearance - use 'departure'.
Worked example
TORA 4000 m, clearway 150 m, stopway 60 m: TODA = 4150 m, ASDA = 4060 m, LDA = 4000 m. An intersection departure reducing TORA to 3600 m reduces TODA and ASDA by the same 400 m because clearway and stopway are unchanged.